Скачать или смотреть How to Safely Upload Files in Python Using Requests

Learn how to avoid `PermissionError` issues when uploading files in Python with the `Requests` library by ensuring proper file handling.
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This video is based on the question https://stackoverflow.com/q/63358686/ asked by the user 'Nalin Angrish' ( https://stackoverflow.com/u/12025232/ ) and on the answer https://stackoverflow.com/a/63358740/ provided by the user 'Just for fun' ( https://stackoverflow.com/u/14002447/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Uploading Files Safely in Python: Avoiding PermissionError Issues

When working with file uploads in Python using the Requests library, many developers encounter a common problem: the dreaded PermissionError. This error typically arises when the program attempts to delete a file that is still open for reading or writing. In this guide, we’ll break down how to properly handle file uploads to avoid this issue.

The Problem: Understanding the PermissionError

In a project where you need to upload text files to a Flask server, the following code seemed like a practical approach:

[[See Video to Reveal this Text or Code Snippet]]

However, despite wrapping the POST request in a with statement to ensure that resources are freed, a PermissionError occurs:

[[See Video to Reveal this Text or Code Snippet]]

This can be frustrating and confusing. You've done everything correctly, so what went wrong?

The Cause of the Issue

The root of the problem lies in how the file is opened for uploading:

[[See Video to Reveal this Text or Code Snippet]]

In this line, the file is opened for reading but not closed properly before you attempt to delete it with os.remove. Because the file handle is still active, the operating system prevents deletion, resulting in a PermissionError.

The Solution: Use Context Managers for File Handling

To solve this issue, you should also employ a with statement when opening the file for uploading. This ensures that the file is properly closed after the POST request is complete, allowing subsequent file operations (like deletion) to proceed without error.

Here’s how you can modify your code:

Revised Code Example

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the Changes

Context Manager for File Reading: By using with open(...) as file, we ensure that the file is closed immediately after the upload is done.

Safe Deletion: Now that the file is no longer open, os.remove(...) can be safely called without any errors.

Conclusion

When uploading files in Python, never underestimate the importance of properly managing file resources. By using context managers (with statements), you protect your program from common pitfalls like PermissionError while keeping your code clean and efficient. Enjoy your Python programming!